Yes, but the problem with this is that you don't know until it happens. And most of the members who ask about keeping their betta with other fish are less experienced, they usually say this. I have kept fish for 30 years, and I had multiple tanks in a dedicated fish room. I always had tank space if needed; it rarely was, since I would never experiment against nature. I learned some 30 years ago that a betta can easily eat a neon tetra. I would never be so foolish as to even attempt to put any fish in with a male betta, but if such a situation were to occur and didn't work, I at least had tank space available for the poor fish. I very much doubt that new aquarists have this luxury. Which is why I believe it is better for the fish to assume it/they will be normal for the species--a betta is not a community fish and should be housed alone. It is a risk to assume that somehow the betta you have is abnormal and will behave contrary to its genetic programming, and the experiment will work just because you want it. This is a cruel and inhumane approach to keeping fish, both for the betta and the tankmates.